Index: lib/Object/MachOObjectFile.cpp
===================================================================
--- lib/Object/MachOObjectFile.cpp
+++ lib/Object/MachOObjectFile.cpp
@@ -1659,6 +1659,10 @@
 Expected<StringRef> MachOObjectFile::getSymbolName(DataRefImpl Symb) const {
   StringRef StringTable = getStringTableData();
   MachO::nlist_base Entry = getSymbolTableEntryBase(*this, Symb);
+  if (Entry.n_strx == 0) {
+    // contents of the StringTable at n_strx 0 are not defined
+    return StringRef();
+  }
   const char *Start = &StringTable.data()[Entry.n_strx];
   if (Start < getData().begin() || Start >= getData().end()) {
     return malformedError("bad string index: " + Twine(Entry.n_strx) +
Index: test/tools/llvm-nm/X86/macho-dwarf.test
===================================================================
--- /dev/null
+++ test/tools/llvm-nm/X86/macho-dwarf.test
@@ -0,0 +1,5 @@
+# RUN: llvm-nm -ap %p/Inputs/macho-dwarf-x86_64 | cat -e | FileCheck %s
+
+# CHECK-NOT: ENSYM  $
+# CHECK: ENSYM $
+